High-pressure fluid sealing assembly



Feb. 7, 1950 HORNBOSTEL 2,496,471

HIGH-PRESSURE FLUID SEALING ASSEMBLY Filed March 14, 1947 3 sheetsheet lI; five 1mm latwaosnz Feb. 7, 1950 HORNBOSTEL HIGH-PRESSURE FLUIDSEALING ASSEMBLY 3 Sheets-Sheet 2 Filed March l4, 1947 Feb. 7, 1950 L.HORNBOSTEL 2,495,471

HIGH-PRESSURE FLUID SEALING ASSEMBLY 3 Sheets-Sheet 3 Filed March 14,1947 llll mmx QZEZEI: Zar

Moro haeweasrn STATES PATENT OFFICE HIGH-PRESSURE FLUID SEALING ASSEMBLYLloyd Hornbostel, Beloit, Wia, asaignor to Beloit lronhllvorks, Beloit,Win, a corporation of Wilcons UNITED Application March 14, 1947, SerialNo. 734,745

14 Claims.

This invention relates to a fluid sealing assembly for effecting afluidtight seal between a rotating shaft-like member and a stationarycasing member wherein one of such members is exposed to a high pressurefluid. This invention finds particular application as a steam journalfor use in connection with the rotatable drier drum of a paper makingmachine.

While not limited thereto, the application of tween the steam pressurein the drying drum and the ambient pressure. Such an arrangement permitssatisfactory sealing conditions to be obtained without an undesirableincrease in frictional forces between the rotating and stationary partsof the seal elements. Therefore higher fluid pressures may be moreeffectively sealed without reducing seal life, as compared with sealconstructions heretofore known, or, at low this invention to the drierdrum of a paper mak- -10 fluid pressures, more emcient sealing actionwith ing machine constitutes a good illustration of reduced frictionallosses is obtainable. the unique and desirable features of a fluid seal-It will of course be recognized by those skilled ing assembly embodyingthis invention. The in the art that any reduction in frictional lossesdrier drum of a paper making machine is genproduces a correspondingincrease in life of the erally steam heated and rotates when operating.15 wearing parts of the seal and hence seal con- The steam for heatingthe drum is usually fed structions embodying this invention will operateor charged thereinto by an inlet pipe extending satisfactorily for amuch longer period than simithrough the hollow back or rear trunnion ofthe lar devices heretofore known. drum. It is generally most convenientto per- Furthermore, a seal construction embodying mit such supply pipeto rotate with the drum s0 this invention may be rapid disassembled andthat, in effect, the supply pipe constitutes an assembled for inspectionor repair purposes. axial extension of the drum or the drum shaft.Accordingly. it is an object of this invention to It is thereforenecessary to provide a stationary provide an improved fluid sealingassembly for housing or coupling for connecting the rotating rotatingmembers exposed to high pressure fluids. pipe with a suitable source forsupplying steam Another object of this invention is to simplify to thedrum. To prevent leakage between the the construction of steam joints orfluid pressure rotating pipe and the stationary coupling, seals packingjoints for rotatable members exposed must be provided but these sealsshould not into high pressure fluids. such as the dryin drums terferewith free fiow of steam into the pipe nor of paper making machines, andto improve the should they impart appreciable frictional re- 39eficiency, operation and dependability of such sistance to therotational movement of the drum joints. due to rubbing between rotatingand stationary A principal object of this invention is to proparts ofthe seal. vide a high pressure fluid seal assembly for a Heretofore,seals of known construction were rotating shaft-like member wherein aplurality not satisfactory when it was desired to use relaof individualseal elements are employed and tively high steam pressures in the drum.With the pressure difference across any one seal eleseals of knownconstructions, the redesign of ment is predetermined so as to neverexceed a such seal to withstand higher steam pressures predeterminedfraction of the total pressure difnecessarily involved a substantialincrease in the ference between the maximum pressure of the frictionaldrag between the rotating and station- 40 fluid and the ambientpressure. ary parts of the seal which resulted in the rapid A particularobject of this invention is to prodeterioration of the seal,necessitating the frevide a high pressure fluid seal for a rotatingquent shut down of the machine for replaceshaft-like member wherein achamber is proment. vided adjacent the rotating member having oneAnother requirement for the steam journals of wall defined by a sealexposed to the maximum a drier drum of a paper making machine is thatfluid pressure and another wall defined by a seal such journal becapable of rapid disassembly for exposed to ambient pressure and whereinthe inspection or for repair and replacement of the pressure in suchchamber is maintained at a sealing devices. value intermediate themaximum fluid pressure In a shaft seal embodying the present invenandthe ambient fluid pressure so that the prestion, a plurality ofindividual seal elements are provided to form a single seal unit, andthe fluid pressure drop across each of such plurality of seal elementsis maintained at a predetermined fraction of the entire difierence inpressure besure drop across either of the individual seals may bereduced to a predetermined fraction of the difference between themaximum pressure and the ambient pressure.

A further object of this invention is to provide a steam journal for arotating shaft-like member wherein a plurality of individual sealelements are employed to prevent leakage of steam to the surroundingatmosphere and wherein each of the individual seal elements includes abellows which not only permits relative contraction and expansionmovement of the rotating member with respect to the stationary portionof the journal but also exerts a compressive force upon the sealingfaces of the seal element to increase the efliciency of the sealingaction.

The specific nature of the invention as well as other objects andadvantages thereof will become apparent to those skilled in the art fromthe following detailed description of the annexed sheets of drawingswhich, by way of preferred example only, illustrate one specificembodiment of the invention.

On the drawings:

Figure 1 is a schematic view, partly in section, of a fluid shaft sealembodying this invention, shown in assembly with a rotating drying drumof a paper making machine.

Figure 2 is an enlarged scale, sectional view taken on a diametral planethrough the shaft sealing element of Figure l.

Figure 3 is an elevational view of the sealing surface of one sealflange.

Figure 4 is a sectional view taken on the plan IV-IV of Fig. 2. V

Figure 5 is an exploded view of the components shown assembled in Fig.2.

As shown on the drawings:'

The drawings should be understood as being more or less of a schematiccharacter for the purpose of disclosing typical or preferred forms ofthe improvements that are contemplated herein, and in these drawings,like reference characters identify the same parts in the difierentviews.

In Figure 1, the numeral ll identifies a rotatable element which issubject to fluid pressure and for which a shaft seal is required, forexample, the drier drum of a paper making machine, having a rear or backend trunnion II that is journaled in a bearing i2 mounted in an annularsupport I! at the upper end of a pedestal ll. The outer portion of thebearing i2 is provided with an annular flange II to which a bearingendcap I! is anchored by means of bolts or the like. As best shown inFigures 2 and 5, the bearing cap I! is hollow and its outer end wall iscentrally apertured as indicated at II to permit the end of hollowtrunnion II to pass therethrough. It will be understood that the bore ofhollow trunnion II is in fluid communication with the interior of thedrum II.

The projecting end of trunnion Ii is provided with an integral, inwardlyprojecting flange Ila and an annular coupling 2. having a central boreIla is rigidly secured thereto by bolts 2!. The outer face of coupling22 is counterbored to proride a recess 2.17 which snugly receives theflanged end 220 of a pipe 22. Suitable bolts 23 rigidly secure pipe 22to coupling 2| in axial alignment with trunnion ll. Pipe 22 therefore,in effect, constitutes an axial, shaft-like extension of the trunnion iI.

A seal support casing 24 is provided which may be conveniently formed byassembly of three separate pieces which are held in rigid assembly bybolts 26. Thus seal'supp rt 24 comprises a webbed primary support member244 which is rigidly but axially adjustably secured by bolt members 28to an integral flange ila provided on bearing end caps l1. Immediatelyadjacent the webbed member 24a, an annular ring 24b is mounted which hasa flange portion 24d projecting radially inwardly to deflne a centralaperture surrounding but spaced from the central portion of the pipe 22.Lastly, support casing 24 comprises an end bell 24c which is ofBenerally cup-shaped configuration and provided in its base portion withan apertured hub 2|e having apipe coupling flange 2|] by whichconnection may be made through a conduit 2| (Figure 1) with a suitablesource of high pressure fluid, in this particular case, a source of highpressure steam. I

The outer end of pipe 22 terminates short of the inner face of the hub24c of end casing- 240. An annular seal backing flange I2 is secured tosuch end portion of the pipe 22 by bolts 34 as is a generally tubularfluid guide member I. Fluid guide member ll has a radial flange "athrough which the bolts 34 Pass and an axially extending tubular portionIlb proiecting into the aperture of hub 24c of the end casing 24c. Theouter end of the tubular portion 26b is deformed outwardly as indicatedat "c and the resulting arrangement is such that fluid entering thecasing 24 is primarily directed into the bore of pipe 22, yet theinterior of end casing 240 is in fluid communication therewith andsubject to the same fluid pressure.

The pipe 22 is also provided with an outwardly projecting flange portion22c which is disposed on the inner side of ring 2lb approximately thesame distance therefrom as the seal backing flange 32. A sealing unit 3|is assembled against backing flange 32 while a similar sealing unit 40is assembled against pipe flange 220; Each of the seal units 20 and llincludes respectively annular sealing rings a and "a, pressure plates aband b, seal springs "c and and bellows elements "d and d.

The outer radial face of pipe flange 22c defines a generally radialseating surface for the seal .unit ll while the inner radial surface ofseal thesealunitll. Aswillbebroughtoutindetail later, the seal unit llseals against radially inward flow of fluid while the seal unit Illseals against the tendency of the fluid to flow radially outwardly.Accordingly. the seal ring "a is of slightly tapered cross-sectionalconfiguration, diminishing in thickness toward the center there of,while the seal ring a is reversely tapered.

The radial sealing faces of backing flange 32 and pressure plate 28b ofthe seal unit 3| are recessed in the manner indicated in Figure 3 toimprove the sealing action thereof and to reduce the friction betweenthe stationary and movable parts of the seal unit. A plurality of spacedrecesses 42 are provided in both of the opposed radial sealing faces ofseal unit II and the nonrecessed surface defines a continuous annularsealing surface 42a which however is of substantially less width thanthe total width of the cooperating seal ring "a. While the recesses 42are circumferentially spaced, they are provided with projecting portionsno at each arcuate end between which is defined a radially extendingsealing surface 42b of generally bottle neck configuration. The innerportions of sealing surfaces |2b are extended arcuately but do not join,being separated by small width channels 42d communicatlngwith recesses42. With a sealing face configuration as described. it has been foundthat the fluid sealing action is greatly improved,

there being a negligible amount of leakage past the sealing surfaces.Furthermore any foreign objects that flnd their way between the sealinssurfaces and which would ordinarily tend to scratch or mar such surfacesare trapped in the recesses 42. It has been further observed that thefrictional losses in sea] units embodying the described configurationare substantially reduced over that of constructions heretoforeemployed.

The radial sealing faces of the seal unit 4| are shaped in a similarmanner to those of seal unit 3| but, of course, are of reversedconfiguration inasmuch as the direction of leakage fluid flow throughthe seal is reversed. As shown in Figure 4, the outer portions of thesealing faces of seal unit 40 are provided with circumferentially spacedrecesses 44 which thereby define a continuous, annular sealing face 44aadjacent the inner portion of the sealing face. The recesses 44 areprovided with arcuate extensions 1) to define sealing surfaces 440 ofbottleneck configuration extending radially to the periphery of thesealing face. Similar advantages as recounted in connection with thesealing face construction of Figure 3 are obtained with the sealing faceconfiguration of Figure 4.

The seal springs 38c and 40c operate respectively between the inwardlyprojecting flange portion 24d of ring 24b and the pressure plates 38band 40b. The seal springs of course produce a snug engagement betweenthe opposed radial sealing faces of each seal unit and the correspondingseal ring.

The bellows elements 38d and 40d respectively extend from internallyprojecting flange portion 240! to the non-sealing faces of the pressureplates 38b and lb. The opposite ends of the bellows elements arerespectively sealed to their supporting structures by clamping rings 46and it is therefore apparent that the bellows elements cooperatewith'the external surface of pipe 22, flange portion 24d and each of theseal units SI and 40 to define an enclosed compartment or chamber 48.The seal unit 38 separates compartment 48 from the high pressure fluidapplied to the drier drum through the central aperture in the end casing240. The seal unit 40, however, separates the chamber 48 from theambient pressure surrounding the mechanism, which of course, isgenerally atmospheric pressure. It is therefore apparent that if thechamber 48 is supplied with fluid at a pressure of a value intermediateatmospheric pressure and the high pressure within drier drum Hi, thenthe pressure drop across each of the seal units 38 and 40 will be only afraction of the total pressure difference between atmospheric pressureand the fluid pressure existing within drier drum iii. For example, ifthe chamber 48 is supplied with fluid pressure of a value equal toone-half of the difference between the high pressure in the drier drumii and atmospheric pressure, then the pressure drop across each of theseal units 38 and 40 will be exactly one-half of the total differencebetween the high pressure and the ambient pressure.

Any one of several well known forms of pressure control mechanism can beprovided to maintain the pressure within chamber 48 at any selectedvalue. While it is of course possible to provide fluid pressure from aseparate source, I preferably derive the intermediate fluid pressure forchamber 4| from the high pressure source for the drier drum ll through apressure reducing regulator ll (Fig. 1). In this manner, the pressuredrop across each of the seal units l8 will and 40 may be maintained at apredetermined fraction of the total pressure diflerence irrespective ofvariation in the high pressure.

Thus a pipe We may be tapped into the wall of end casing 24c to supplyhigh pressure fluid to one side of the regulating chamber lb of thepressure regulating valve mechanism 0!. A pipe 50c connects the otherside of regulating chamber "b to the interior of chamber 48 through asuitable radial passage 24g provided in ring 24b. The transfer of fluidthrough the regulating chamber 501; is controlled by a valve bid whichis in turn controlled by a pair of diaphragms lie and 50! respectivelyconnected to the high and low pressure conduits 50a and "c of thepressure regulating mechanism ll.

Since condensate will tend to collect within chamber 48, I preferablyemploy a condensate drain comprising a radial passage 24k. in ring 24bwhich communicates through a pipe 52 with a conventional steam trapdrain I.

It is therefore apparent that the efiective fluid pressure in chamber 48may be readily selected by adjustment of pressure regulating mechanismill at any value intermediate the maximum pressure existing within thedrier drum and the atmospheric pressure. It is further apparent that ahigher pressure exists outside seal unit 3' than on the inside, whilethe pressure conditions are exactly reversed in seal unit 40, therebeing a higher pressure on the inside thereof than on the outside. Thiscondition explains the necessity for the reverse tapering of the sealrings 38a and 4011 respectively.

In addition to forming a wall of the intermediate pressure chamber 48,the bellows elements 38d and 40d, respectively, perform anotherimportant function in that they permit the sealing action of seal units38 and. 40 to be efl'iciently maintained irrespective of contraction andexpansion movements of the pipe 22 or the trunnion II with respect tothe stationary casing 24. Obviously, when steam is initially supplied tothe drier drum ill, there will be an appreciable axial elongation of thedrum Ill and trunnion ll resulting in an axial movement of the pipe 22with respect to the stationary casing 24. The bellows 38d and 40d expandor contract as the case may be to freely accommodate such relativemovements without adversely affecting the engagement of the seal rings38a and 40a with their sealing surfaces, or the pressure conditionswithin intermediate pressure chamber 48. Lastly, the bellows element 40dassists in maintaining a compressive force on the seal ring 40a inasmuchas the pressure difference between the inside and outside walls ofbellows unit 40d is in the direction to tend to cause the bellows unitto expand and therefore exert axial pressure against the sealing facesof seal unit 4'.

While in the particular example described, only one intermediatepressure chamber 48 was utilized, it will be apparent to those skilledin the art that even greater fractional reduction of the effective fluidpressures across each of the individual seal units may be obtained byproviding additional intermediate pressure chambers and cooperating sealunits so arranged that leakage fluid through the seals successivelytraverses such chambers. For example, if one additional intermediatepressure chamber were provided in a series connected arrangement withthe intermediate pressure chamber 48, then the pressure across each ofthe individual seal elements corresponding to the seal elements 38 and4| could be ambient pressure.

reduced to one-third of the total pressure diflerence between the highpressure within the drier drum and atmospheric pressure. Thereforeextremely high fluid pressures can be safely and efiicientlyaccommodated by shaft sealing assemblies embodying this inventionwithout increasing the size of the individual seal units or adverselyaffecting the normal life of such seal units.

It will, of course, be understood that various details of constructionmay be modified through a wide range without departing from theprinciples of this invention and it is, therefore, not the purpose tolimit the patent grantedhereon otherwise than necessitated by the scopeof the appended claims.

I claim as my invention:

1. A' high pressure fluid sealing assembly for a rotating, shaft-likemember having a portion thereof exposed to high pressure fluidcomprising stationary means defining a first chamber surrounding aportion of said shaft-like member, and including a pair of axiallyspaced seals engageable with said shaft-like member in malingrelationship, means defining a second chamber surrounding a portion ofthe walls of said first chamber and including one of said seals, meansconnecting said second chamber in fluid communication with said highpressure fluid, and means for supplying said first chamber with fluid ata pressure intermediate said high pressure and the 2. A sealing assemblyfor a movable member exposed to high pressure fluid comprisingstationary means defining a chamber, sealing means operatively disposedbetween said stationary means and said movable member, whereby fluidleaking past said sealing means enters said chamber, means formaintaining a fluid pressure in said chamber of a value intermediatesaid high pressure and the ambient pressure 'exteriorly of said chamber,and means responsive to. said intermediate pressure for applying acompressive force on said sealing means substantially perpendicular tothe sealing faces thereof.

3. A sealing assembly for a movable member exposed to high pressurefluid comprising stationary means deflning a chamber, sealing meansoperatively disposed between said stationary means and said movablemember whereby fluid leaking past said sealing means enters saidchamber, means for maintaining a fluid pressure in said chamber of avalue intermediate said high pressure and the ambient pressureexteriorly of said chamber, said chamber defining means including abellows element to permit expansion and contraction movement of saidmovable member without adversely affecting the operation of said sealingmeans.

4. In combination, a hollow rotating member adapted to contain a fluidunder pressure, a stationary casing defining a first chamber in fluidcommunication with the hollow portion of said rotating member, a sealoperatively disposed between said casing and said rotating member,whereby one side of said seal is subjected to said fluid pressure, meansdefining a second chamber enclosing the other side of said seal, andmeans for maintaining a fluid pressure in said second chamber of a valueintermediate said pressure in said rotating member and the ambientpressure.

5. In combination, a hollow rotating member adapted to contain a fluidunder pressure, a stationary casing defining a first chamber in fluidcommunication with the hollowv portion of said rotating m m means osupplying h gh pres- 8 surefiuidtosaidhoilowportionoftherotsting memberthrough said casing, a seal operatively disposed between said casing andsaid rotating member whereby on side of said seal is subiectedtosaidhigh fluid pressure, means definingasecand chamber enclosin theother side of said seal. and means for maintaining a fluid pressure insaid second chamber of a value intermediate said pressure in saidrotating member and the ambient pressure.

6. In combination, a hollow rotating member adapted to contain a fluidunder pressure, a stationsry casing defining a first chamber in fluidcommunication with the hollow portion of said rotating member, a sealoperatively disposed between said casing and said rotating member,whereby one side of said seal is subject to said high fluid pressure,means defining a second chamber enclosing the other side of said seal, asecond seal operatively disposed between said rotating member and saidsecond chamber and having one side thereof exposed to the fluid pressurein said second chamber and the other side exposed to an ambientpressure, and means for maintaining a fluid pressure in said secondchamber of a value intermediate said pressure in said first chamber andsaid ambient pressure;

'1. In combination, a hollow rotating shaft, a stationary casingsurroundin an end portion of said shaft and partially defining a firstchamber in fluid communication with the hollow portion of said shaft,means for supplying high pressure fluid to said first chamber, a firstannular sealing means surrounding said shaft and cooperating with saidshaft casing to complete the walls of said first chamber, a secondannular sealing means surrounding said shaft and cooperating with saidfirst sealing means and said shaft to define a second chamber sealedfrom the fluid pressure in said flrstchamber and the ambient pressure,and means for maintaining a fluid pressure in said second chamber of. avalue intermediate the said high fluid pressure and the ambientpressure.

8. In combination, a hollow rotating shaft, a stationary casingsurroundin an end portion of said shaft, an internally projecting flangeon said casing surrounding said shaft, a pair of seal assembliescooperating with portions of said shaft respectively disposed onopposite sides of said flange, a pair of bellows elements sealinglyconnecting said flange respectively with said seal assemblies, therebydefining a first chamber in fluid communication with the hollow portionof said shaft and a second sealed chamber intermediate said sealingassemblies, means for supplying high pressure fiuld to said firstchamber, and means for maintaining a fluid pressure in said secondchamber of a value intermediate said high pressure and the ambientpressure.

9. In combination, a hollow rotating shaft, a stationary casingsurrounding an end portion of said shaft, an internallyprojecting'flange on said casing surrounding said shaft, a pair ofexternal flanges on said shaft defining opposed, generally radialsealing faces, annular seal rings respectively abutting said sealingfaces, annular pressure plates respectively abutting said seal rings,resilient means operating between said internal flange and said pressureplates respectively to axially compress said seal rings, and a pair ofbellows elements sealingly connecting said flange respectively with saidpressure plates, thereby permitting relative expansion and contractionmovement of said shaft with respect to said stationary casing.

10. In combination, a hollow rotating shaft, a stationary casingsurrounding an end portion of said shaft, an internally projectingfiange on said casing surrounding said shaft, a pair of external flangeson said shaft defining opposed, generally radial sealing faces, annularseal rings respectively abutting said sealing faces, annular pressureplates respectively abutting said seal rings, resilient means operatingbetween said internal flange and said pressure plates respectively toaxially compress said seal rings, a pair of bellows elements sea-linglyconnecting said flange respec tively with said pressure plates, therebydefining a first chamber in fluid communication with the hollow portionof said shaft and a second sealed chamber intermediate said seal rings,means for supplying high pressure fluid to said first chamber, and meansfor maintaining a pressure in said second chamber of a valueintermediate said high pressure and the ambient pressure.

11. In combination, a hollow rotating member adapted to contain a fluidunder pressure, a stationary casing defining a first chamber in fluidcommunication with the hollow portion of said rotating member, means forsupplying high pressure fluid to said hollow portion of the rotatingmember through said casing, a seal operatively disposed between saidcasing and said rotating member whereby one side of said seal issubjected to said high fluid pressure, means defining a second chamberenclosing the other side of said seal, means for maintaining a fluidpressure in said second chamber of a value intermediate said pressure insaid rotating member and the ambient pressure, and means for derivingsaid intermediate fluid pressure from said high pressure fluid.

12. In combination, a hollow rotating shaft, a stationary casingsurrounding an end portion of said shaft, an internally projectingflange on said casing surrounding said shaft, a pair of external flangeson said shaft defining opposed, generally radial sealing faces, annularseal rings respectively abutting said sealing faces, annular pressureplates respectively abutting said seal rings, resilient means operatingbetween said internal flange and said pressure plates respectively toaxially compress said seal rings, a pair of bellows elements sealinglyconnecting said flange respectively with said pressure plates, therebydefining a first chamber in fluid communication with the hollow portionof said shaft and a second sealed chamber intermediate said seal rings,means for supplying high pressure fluid to said first chamber, means formaintaining a pressure in said second chamber of a value intermediatesaid high pressure and the ambient pressure, and means for deriving saidintermediate fluid pressure from said high pressure fluid.

13. A sealing assembly for a rotary shaft-like member adapted totransmit fluid under high pressure, comprising stationary means defininga first chamber in fluid communication with the interior of saidshaft-like member, a seal having one side thereof exposed to highpressure disposed between said stationary means and said rotatingmember, means defining a second chamber enclosing the other side of saidseal, and means for maintaining a fluid pressure in said second chamberat a value intermediate said high pressure and the ambient pressure.

14. A sealing assembly for a rotary shaft-like member adapted totransmit fluid under high pressure, comprising means defining a firstchamber in fluid communication with the interior of said shaft-likemember, a pair of axially spaced seals engageable with said shaft-likemember in sealing relationship, a side of one of said seals beingexposed to said high pressure and a side of the other of said seals toambient pressure, means defining a second chamber extending between saidseals, and means for maintaining a fluid pressure in said second chamberat a value intermediate said high pressure and the ambient pressure.

LLOYD HORNBOSTEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,996,780 Wheeler Apr. 9, 19352,381,432 Bratton Aug. 7, 1945 2,384,281 Carter Sept. 4, 1945 2,402,224Hornbostel June 18, 1946 2,418,620 Brumagln Apr. 8, 1947

